Prolamine coatings for taste masking

Abstract

Prolamine fractions of grain proteins, applied as a single coating in weight ratios of 5 to 100% relative to the active substance being coated, result in the production of a liquid suspension which effectively masks the taste of orally administered drugs which often are extremely bitter. The taste masking is stable over prolonged periods of storage time of the suspension. The prolamine coating does not restrict the immediate bioavailability of the active substance. Prolamine coating is effective in masking the taste of antibiotics, vitamins, dietary fiber, analgesics, enzymes and hormones. Zein, gliadin or a mixture thereof, particularly in combination with between 2.5 and 15% of a water insoluble vegetable source oil or a wax capable of plasticizing the prolamine fraction, when applied to particles of drugs or nutritional supplements, to an effective thickness of about 1 to about 35 micrometers, are particularly effective in preventing the release of the active substance from the encapsulated particle and also in masking the unpleasant taste of the coated active substance.

What is claimed is: 
     
       1. A method for preparing a suspension of an encapsulated active substance, said suspension having the characteristics of stable taste masking and immediate release of the active substance in the gastrointestinal tract, said method consisting essentially of the steps of: (a) forming particles of an active substance selected from the group consisting of clarithromycin and erythromycin by dissolving said substance in a solvent, drying and sieving the resultant powder to yield particles having a size in the range of between about 175 microns and about 420 microns;   (b) encapsulating the particles with a single outer coat by contacting the particles with a coating solution comprising a mixture of a prolamine and a hydrophobic plasticizer selected from water-insoluble vegetable source oils and waxes wherein said oils and waxes have a fatty acid chain length of about 6 to about22 carbon atoms;   (c) collecting the coated particles; and   (d) suspending the coated particles in a solution having a final pH greater than about 6.5.   
     
     
       2. The method according to claim 1 wherein said prolamine comprises an amount of from about 30% to about 70% by weight of the sum of the weights of said active agent and said single coating layer, and wherein the ratio of prolamine to said plasticizers and hydrophobic substances in said coating layer is from 40:1 to 4:1. 
     
     
       3. The method according to claim 2 wherein said prolamine comprises an amount of from about 40% to about 60% by weight of the sum of the weights of said active agent and said single coating layer. 
     
     
       4. The method according to claim 2, wherein said ratio of prolamine to hydrophobic plasticizers is from 20:1 to 20:3. 
     
     
       5. The method according to claim 1, wherein the weight ratio of said active substance to said coating layer is from 20:1 to 1:1 and the coating is from about 1 to about 35 micrometers thick. 
     
     
       6. The method according to any one of claims 1 through 4 and 5 wherein the prolamine is selected from the group consisting of zein, giladin and hordein. 
     
     
       7. The method according to any one of claims 1 through 4 and 5 wherein the prolamine is zein. 
     
     
       8. A method for preparing a suspension of an encapsulated active substance, said suspension having the characteristics of stable taste masking and immediate release of the active substance in the gastrointestinal tract; said method consisting essentially of the steps of: (a) forming particles of an active substance by dissolving said substance in a solvent, drying and sieving the resultant powder to yield particles having a size in the range of between about 175 microns and about 420 microns.   (b) encapsulating the particles with a single outer coat by contacting the particles with a coating solution comprising a mixture of a prolamine and a hydrophobic plasticizer selected from the group consisting of triethylene glycol, propylene glycol, oleic acid, lactic acid, acetamide, ethylene glycol monooleate, glycerin, glyceryl monostearate, dibutyl tartrate, tricresyl phosphate, vegetable oils, animals fats, monoglycerides, diglycerides, triglycerides, acetylated monoglycerides, acetylated diglycerides, and mixtures thereof;   (c) collecting the coated particles; and   (d) suspending the coated particles in a solution having a final pH greater than about 6.5.   
     
     
       9. The method according to claim 8 wherein said prolamine comprises an amount of from about 30% to about 70% by weight of the sum of the weights of said active agent and said single coating layer, and wherein the ratio of prolamine to said plasticizers and hydrophobic substances in said coating layer is from 40:1 to 4:1. 
     
     
       10. The method according to claim 9 wherein said prolamine comprises an amount of from about 40% to about 60% by weight of the sum of the weights of said active agent and said single coating layer. 
     
     
       11. The method according to claim 8 wherein said ratio of prolamine to hydrophobic plasticizers is from 20:1 to 20:3. 
     
     
       12. The method according to claim 8 wherein the weight ratio of said active substance to said coating layer is from 20:1 to 1:1 and the coating is from about 1 to about 35 micrometers thick. 
     
     
       13. The method according to claim 8 wherein said active substance is a nutritional supplement selected from the group consisting of proteins, amino acids, vitamins and dietary fiber. 
     
     
       14. The method according to claim 8 wherein the prolamine is selected from the group consisting of zein, gliadin and hordein. 
     
     
       15. The method according to claim 8 wherein the prolamine is zein. 
     
     
       16. The method according to claim 8 wherein said hydrophobic plasticizer is a vegetable oil selected from the group consisting of palm oil, palm kernel oil, soybean oil, rapeseed oil, rice bran oil, sunflower oil, safflower oil, coconut oil, castor oil and MCT oil. 
     
     
       17. The method according to claim 8 wherein the active substance is selected from the group consisting of analgesics, antibiotics, anti-depressants, antivirals, antibodies, immunomodulators, oncolytics, immunogens, hormones, vaccines, enzymes and nutritional supplements. 
     
     
       18. The method according to claim 8 wherein said active substance is an antibiotic selected from the group consisting of clarithromycin and erythromycin.